This claim is actually a come-down from the 1988 claim on the cover of Newsweek that all scientists agree. In either case, the claim is meant to satisfy the non-expert that he or she has no need to understand the science. Mere agreement with the 97% will indicate that one is a supporter of science and superior to anyone denying disaster. This actually satisfies a psychological need for many people. The claim is made by a number of individuals and there are a number of ways in which the claim is presented. A thorough debunking has been given in the Wall Street Journal by Bast and Spencer. One of the dodges is to poll scientists as to whether they agree that CO2 levels in the atmosphere have increased, that the Earth has been warming (albeit only a little) and that man has played some part. This is, indeed, something almost all of us can agree on, but which has no obvious implication of danger. Nonetheless this is portrayed as support for catastrophism. Other dodges involve looking at a large number of abstracts where only a few actually deal with danger. If among these few, 97% support catastrophism, the 97% is presented as pertaining to the much larger totality of abstracts.
RICHARD LINDZEN, Professor of Atmospheric Science, MIT Thoughts on the Public Discourse over Climate Change